1. Technical Field
The present invention relates to an apparatus and a method of manufacturing metal nanoparticles and more particularly, to an apparatus and a method of manufacturing nanoparticles in continuous mass scale.
2. Description of the Related Art
There is a large demand for metal nanoparticles as conductive materials or recording materials in various industry fields such as electronic components, coatings, condensers, magnetic tapes, paints, etc. since metal nanoparticles having a nano size exhibits unique characteristics. Accordingly, a great deal of development research is under way on mass production of metal nanoparticles.
Metal nanoparticles have been generally manufactured by various method such as a vapor phase method which supplies metal vapor vaporized to a high temperature, allows collision with gas molecule, and quickly freezes to provide fine particles, a liquid phase method which allows reduction of metal ions by adding a reducing agent into a solution where the metal ions are dissolved, a solid phase method and a mechanical method, etc.
The liquid phase method among those methods has been relatively widely used since it is economical and requires simple processes and mild reaction conditions. A typical liquid phase method produces nanoparticles while nucleation and its growth occur with addition of a metal cation solution and a reducing agent solution into a reactor equipped with a stirrer. Here, uniform metal nanoparticles may be obtained by controlling temperature or concentration of a precursor to induce a uniform reaction in a micro region.
However, it requires a large reactor for mass production and causes ununiform internal temperature of the reactor and uniform concentration of a precursor when the concentration of a precursor is rapidly increased. This ununiformity adversely affect the size distribution of nanoparticles, so that it is an obstacle to manufacture uniform metal nanoparticles.
Methods for continuously manufacturing nanoparticles by employing continuous reaction in a micro channel have been introduced in order to resolve such problems. When a precursor solution is continuously run to a heated micro channel, a temperature of the precursor solution can be raised quickly to a reaction temperature and particles can be formed at the micro region, so that the uniformity of particles can be easily controlled. However, since most of continuous reactions including one disclosed in JP Patent Publication no. 2003-193119 use channels only having a diameter of several micrometers to several hundred nanometers, the channels may be easily blocked during the continuous reaction.
In order to resolve this problem, KR Patent Publication No. 2006-0107695 discloses use of a channel having a wider diameter of 1 to 10 mm and a micro emulsion reaction to prevent the ununiformity caused by using the wider channel. However, the micro emulsion can be only efficient when a low concentration of a precursor is used and a channel having a narrow diameter of about 1 mm is used. Since isolation of produced particles from the emulsion is difficult, the final yield is too low to manufacture nanoparticles in mass scale.
Therefore, a method for manufacturing metal nanoparticles in mass scale is highly demanded.